HAVING NOT EXISTS
SELECT DEPT.DEPT_NO, AVG (EMP.EMP_SAL)
FROM DEPT, EMP
WHERE DEPT.DEPT_NO = EMP.DEPT_NO
GROUP BY DEPT.DEPT_NO
HAVING NOT EXISTS (SELECT EMP1.DEPT_NO
FROM EMP EMP1
WHERE EMP1.DEPT_NO <> DEPT.DEPT_NO
GROUP BY EMP1.DEPT_NO
HAVING AVG (EMP1.EMP_SAL)= AVG (EMP.EMP_SAL));
